The U.S. National Security Agency is reported to have implanted malicious software in nearly 100,000 computers worldwide -- allowing the U.S. to conduct surveillance on those machines and create a digital highway for launching cyberattacks.

The New York Times said the NSA inserted most of the software by gaining access to computer networks, but had also increasingly made use of a secret technology that enables it to enter and alter data in computers even if they were not connected to the Internet.

The report cited NSA documents, U.S. officials and computer experts.

The Times story comes as President Barack Obama prepares to announce Friday changes he wants to make in the scope of the NSA spying. The Times reported that aides to Obama said he would curtail the agency's surveillance, but not adopt the most far-reaching recommendations of a White House review panel.

It said the president would limit access to the agency's vast collection of information about the millions of telephone calls Americans make, place new safeguards on monitoring the calls of foreign leaders and name an advocate to appear before a secret intelligence court to represent privacy concerns. But the presidential aides said Obama did not plan to send the phone data outside the NSA.

The Times said the NSA has successfully implanted the software into such targets as Russian military networks, systems used by Mexican police and drug cartels, trade groups inside the European Union, and such anti-terrorism partners such as Saudi Arabia, India and Pakistan. The paper said there was no evidence it has implanted its software or used the radio frequency technology inside the United States.

The details are part of the scores of documents leaked by former NSA contractor Edward Snowden. The NSA said Snowden stole 1.7 million documents before fleeing to asylum in Russia even as American authorities have sought his extradition to stand trial in the United States on espionage charges.

The Times said the technology referred to in its story relied on a covert channel of radio waves that could be transmitted from tiny circuit boards and memory cards physically inserted into computers.